Integrated circuits with high voltage capabilities have wide industrial applications, including power management systems for use in automobiles. These integrated circuits include high voltage transistors that operate at a high voltage range (e.g., 80 v to 120 v) and low voltage transistors that operate at a much lower voltage range (e.g., 1 v to 5 v). To protect the low voltage transistors from the high voltage operations, an integrated circuit may adopt one or more isolation schemes. For instance, one scheme involves forming a buried layer (e.g., an N-type buried layer) on top of a bulk substrate (e.g., a P-type substrate) to isolate the high voltage transistors from the low voltage transistors. The buried layer is typically biased at a high voltage corresponding to the operating range of the high voltage transistors, whereas the bulk substrate is typically biased at a ground supply voltage. In some cases, the difference between the high bias voltage and the ground supply voltage may exceed a breakdown voltage threshold of a PN junction between the buried layer and the bulk substrate, thereby causing leakages and impacting the performance and reliability of the integrated circuit.